Particle cosmology is the application of lessons learned in high-energy physics to the study of cosmology. A closely-related and often overlapping field is astroparticle physics, which is the application of high-energy physics to astrophysics.

The basic idea is that our knowledge of the universe is now sufficiently detailed our knowledge of high-energy physics can be directly applied into our computations of the behavior of various astrophysical and cosmological phenomena, to the point where we can even make statements about the properties of high-energy physics by looking at astrophysical and cosmological phenomena.

Examples include the study of ultra high-energy cosmic rays, pulsars, supernovae, and other energetic phenomena, as well as very early times in our universe.